I need a battery that doesn't last

Discussion in 'The Projects Forum' started by mike_in_sd, Feb 11, 2011.

  1. mike_in_sd

    Thread Starter New Member

    Feb 11, 2011
    3
    0
    I bought a dash cam that when you start the car, it automatically turns on and starts recording. So far so good. The problem is I expected the thing to automatically turn off when I turn the car off. It doesn't. It goes to battery power and I have to hit the on/off button OR OR OR ... wait till the battery dies and then it will save the video file before it turns off.

    SOOOOO .. Right now it has a little lith half the size of a piece of gum. And it lasts quite a long time. If I could replace this with a battery that dies quickly It would serve my purpose.

    Maybe I could put something across the batt that would drain it .. or ..
    well .. that what I am asking here.

    tia
    Mike
     
  2. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    Does it go into internal battery power, or does it drain the car battery power?

    There's a circuit posted here that only allows leds to be lit if the engine is running, IIRC, it could be re-purposed to your camera.

    What does the "in_sd" stand for? What's your location?
     
  3. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    I'm betting South Dakota. I see small batteries all the time for small RC aircraft, they take a charge for several minutes, then drain in about the same amount of time. As TOG, the circuit isn't that hard.
     
  4. Audioguru

    New Member

    Dec 20, 2007
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    Replace the battery with a capacitor. Select a value high enough that the circuit has enough time to save the video.
     
  5. wayneh

    Expert

    Sep 9, 2010
    12,139
    3,054
    I think, not at all sure, that a lower voltage at the camera is what will trigger the self-shutdown. It probably looks for a voltage ~.6 of the peak full charge voltage. So if you could find a lower voltage battery, or place a low-ohms resistor in series with the battery, it might still supply enough juice for the safe auto-shutdown, without letting it think it can keep recording.
     
  6. mike_in_sd

    Thread Starter New Member

    Feb 11, 2011
    3
    0
    First off, I'm in San Diego .. and the weather is short sleeves and shorts today .. grin

    What happens is while the cam is running from the car battery, the cam uses that power source and charges the cam battery at the same time.

    When that power is removed, it automatically goes to battery power and when the battery power finally gets too low it will save the current file and shut down.

    The reason I don't just let it do this is that it continuously records in 15min chunks (files) .. for a couple of hrs worth . eating the first ones when it gets full (it loops)

    So If I got in a bad accident and the power was cut and I wasn't able to get to the cam ... it would eventually eat all the good footage.

    I was wondering about the capacitor, but the only thing I am worried about is the lithium charging circuit ... I dont know how finicky it is. I'm not sure about the little RC batt .. I think the reason that it only last a couple of min is the power demand put on it by the RC motor.

    The sensing the lower voltage thing is interesting .. maybe I could replace the battery with one that the voltage level is such that it would trigger the shutdown, but my experience is .. it might be hard to find one that is that exact voltage.

    Im afraid whatever the solution, It is going to have to be limited to "replacing the battery with " type thing because its multi surface, surface mount components and my skill level doesn't go that small.

    Thanks so much for all the replies
    Mike
     
  7. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    Does it run with the battery out of the camera?

    One way to do it is to read the list of "how to prolong the life of a LiIon battery" and break every rule until the battery is essentially ruined. :eek:
     
  8. Audioguru

    New Member

    Dec 20, 2007
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    I have many small RC Li-Po battery cells that are "worn-out". They are discharged in the airplane in about 5 seconds instead of 10 minutes, but then a full charge also takes only 5 seconds instead of 20 minutes.
     
  9. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
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    why don't you just manually turn off the cam when you leave. Is it possible to modify the cam
     
  10. mike_in_sd

    Thread Starter New Member

    Feb 11, 2011
    3
    0
    Thats funny but true. I'll have to see what happens with the internal battery disconnected.

    I'll have to check with my RC buds and try and find a junk batt about the same voltage. If I can that is probably the best solution.

    Oh yea .. turning the cam off manually is exactly what it wants you to do, I just think that ruins the set it and forget it functionality of the dash cam.

    You guys have given me some really good ideas ... Time to try a few of them.

    Thanks
    Mike
     
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